Traffic Environment Recognition Method and System for Carrying Out the Same

ABSTRACT

A traffic environment recognition system includes units for image-processing and information-merging, a radar unit. A network is connected to the image-processing unit. The radar, information-merging, and a vehicle control unit control the traveling operation of the vehicle. The image-processing unit recognizes headway distance, the azimuth, relative speed and width of a preceding vehicle, and the lane position of the host vehicle. The radar unit recognizes headway distance, the azimuth and relative speed of the preceding vehicle. The information-merging unit receives recognition results provided by the image-processing unit. The radar unit through the network, merges and identifies those results. When the recognition results provided by the image-processing unit and the radar unit relate to the same vehicle, output information is produced by the information-merging unit to identify the vehicles as one and the same vehicle and sends the output information through the network to the vehicle control unit.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/224,605, filed Aug. 21, 2002, and issued as U.S. Pat. No. 7,224,290,on May 29, 2007, which claims priority to Japanese patent applicationno. JP 2001-366276, filed Nov. 29, 2001, the disclosure of which isexpressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a traffic environment recognitionmethod and a system for carrying out the same and, more particularly toa traffic environment recognition method suitable for recognizing thetraffic environment of a vehicle, and a traffic environment recognitionsystem for carrying out the traffic environment recognition method to beloaded on a vehicle, such as an automobile.

Importance of active safety measures for recognizing the environment ofa vehicle including lanes and other vehicles, detecting a condition thatmay cause an accident, and warning the driver of the vehicle to takemeasures for avoiding dangers or avoiding accidents by positivelyautomatically controlling the vehicle has progressively increased.Various automotive traffic environment recognition systems have beenproposed.

An active cruise control system (ACC system) has been commerciallymarketed. This ACC system measures the headway distance between the hostvehicle and the preceding vehicle by using a laser radar or a millimeterwave radar, and accelerates or decelerates the host vehicle according tothe measured headway distance to maintain safety vehicle spacing. Thus,the ACC system ensures the safe operation of the vehicle.

However, the laser radar or the millimeter wave radar (hereinafterreferred to simply as “radar”) employed in the ACC system must operateon limited power to measure the headway distance between the hostvehicle and the preceding vehicle traveling a long distance ahead.Therefore, the radar of the ACC system cannot use a vertically andhorizontally wide beam. Consequently, it occurs sometimes that the beamof the radar passes through a space under the preceding vehicle when thepreceding vehicle is a heavy truck and the ACC system fails in detectingthe preceding heavy truck or that the host vehicle nose-dives and theACC system fails in detecting the preceding vehicle when the hostvehicle decelerates sharply to avoid collision against the sharplydecelerated preceding vehicle or a cut-in vehicle.

Since the ACC system is provided with only a single radar and,sometimes, fails in detecting the preceding vehicle in case the hostvehicle nose-dives. Thus, it is essential to the enhancement of thesafety of the vehicle to measure the headway distance between the hostvehicle and the preceding vehicle on the basis of detection signalsprovided by a plurality of sensors, and to improve the reliability ofthe ACC system.

Traffic environment recognition systems provided with a plurality ofsensors are disclosed in, for example, Japanese Patent Laid-open Nos.6-230115 (first reference), 11-44533 (second reference) and 2000-121730(third reference). The traffic environment recognition system mentionedin the first reference determines a headway distance on the basis of animage formed by a camera, and a measurement provided by a millimeterwave radar, and uses the headway distance with higher reliability. Forexample, it is decided that the reliability of information provided bythe camera is low in a rainy or foggy weather, and it is decided thatthe reliability of information provided by the millimeter wave radar islow when information about the road on which the host vehicle istraveling read from a road map of an automotive navigation systemindicates a curve of a small radius or a narrow road. A headway distancedetermined on the basis of the information provided by the camera isused when it is decided that the reliability of the information providedby the camera is high or a headway distance determined on the basis ofthe information provided by the millimeter wave radar is used when it isdecided that the reliability of the information provided by themillimeter wave radar is high.

The traffic environment recognition system mentioned in the secondreference measures the headway distance between the host vehicle and thepreceding vehicle by a radar, calculates the headway distance by aheadway distance measuring unit on the basis of the measured headwaydistance, and controls the traveling speed of the host vehicleautomatically by a vehicle speed control unit on the basis of thecalculated headway distance. Meanwhile, an image input unit provides animage of a scenery extending ahead of the host vehicle, a measuring unitsets a template including a point corresponding to a position ofdistance measurement in the input image provided by the image inputdevice, and a template image storage unit stores a template imageincluded in the template in a storage device. When the radar is unableto measure distance, a control unit executes a control operation to makea correlation calculating unit determine an image area most analogouswith the template image stored in the storage device by a correlationprocess, calculates an estimated position of the preceding vehicle atthe center of the image area, and a headway distance calculating unitcalculates a headway distance on the basis of the estimated position ofthe preceding vehicle.

The traffic environment recognition system mentioned in the thirdreference measures the headway distance between the host vehicle and thepreceding vehicle by a millimeter wave radar, measures the width of thepreceding vehicle by a laser radar in a state where both the millimeterwave radar and the laser radar are detecting the preceding vehicle, anduses a headway distance measured by the millimeter wave radar and avehicle width previously measured by the laser radar in other states.

In a system disclosed in Japanese Patent Laid-open No. 2001-84485, atraffic sign or the like is set on a road extending ahead of a visiblecamera for detection data provided by a visible image sensor and amillimeter wave laser, a visible image-processing unit decides aself-detection ability according to the variation of environmentalcondition from an image of the traffic sign and provides the results ofprocessing, a detection information selecting and processing unitselects automatically an output provided by a detectable vehicledetecting device, and the following operation is performed on the basisof selected detection information to detect abnormal traveling andstoppage.

Those prior art techniques have the following problems because the sameuses information detected and provided by another sensor when thereliability of the single sensor is low.

(1) A decision must be made as to whether or not the same object isrecognized.

(2) The decision needs a complicated procedure when there are aplurality of preceding vehicles or objects.

(3) The extensibility of the system is unsatisfactory in using othersensors including a navigation system in addition to the radar and theimage-processing unit.

The prior art vehicle controller controls a vehicle for traveling on thebasis of detection information provided by the plurality of sensors.However, the vehicle controller must decide whether or not the pluralityof sensors detected the same object, which needs a complicated vehiclecontrol algorithm, control performance is affected adversely, and theimprovement of control function and reliability is difficult.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide atraffic environment recognition method capable of providing highlyreliable traffic environment recognition information, a trafficenvironment recognition system for carrying out the traffic environmentrecognition method, and a vehicle provided with the traffic environmentrecognition system.

According to one aspect of the present invention, a traffic environmentrecognition method includes the steps of: recognizing information abouta plurality of recognition objects representing an environment of avehicle; examining recognition results; merging the recognition resultson the basis of results of examination of the recognition results toobtain merged information; and providing output information produced byadding identification information identifying at least one of theplurality of recognition objects to the merged information.

The traffic environment recognition method may provide outputinformation produced by adding identification information identifyingthe plurality of recognition objects to the merged information.

According to another aspect of the present invention, a trafficenvironment recognition system includes; a plurality of trafficenvironment recognizing means for recognizing the environment of avehicle; and an information merging means for merging recognitionresults provided by the plurality of traffic environment recognizingmeans to provide merged information; wherein the information mergingmeans provides output information produced by adding identificationinformation identifying a recognition object to the recognition resultsprovided by at least two of the plurality of traffic environmentrecognizing means.

The information merging means of the traffic environment recognitionsystem may have the following function:

(1) A function of providing output information produced by addinginformation identifying a plurality of recognition objects toinformation obtained by merging recognition results provided by at leasttwo of the plurality of traffic environment recognizing means;

(2) A function of providing output information produced by adding theresult of decision as to whether or not the merged recognition resultsprovided by at leas two of the plurality of traffic environmentrecognizing means include those relating one and the same recognitionobject as information identifying recognition objects to the mergedrecognition results; or

(3) A function of providing information produced by adding the result ofdecision as to whether or not the merged recognition results provided atleast two of the plurality of traffic environment recognizing meansinclude those relating to the same recognition objects among a pluralityof recognition objects as information identifying the plurality ofrecognition objects to the merged recognition results.

The traffic environment recognition system may further include thefollowing elements:

(1) The plurality of traffic environment recognizing means use differentmediums, respectively, for the recognition of the environment of thevehicle;

(2) The plurality of traffic environment recognizing means use similarmediums for the recognition of the environment of the vehicle;

(3) The plurality of traffic environment recognizing means providesrecognition results respectively provided with message identificationnumbers proper to the traffic environment recognizing means, and theinformation merging means discriminates the recognition results and themessage identification numbers provided by the traffic environmentrecognizing means and provides output information produced by adding amessage identification number corresponding to the result ofdiscrimination to merged recognition results obtained by merging therecognition results provided by the traffic environment recognizingmeans;

(4) The plurality of traffic environment recognizing means provides therecognition results with time information common to the trafficenvironment recognizing means, and the information merging meansidentifies the recognition objects on the basis of the recognitionresults provided by the traffic environment recognizing means and thetime information, and provides output information produced by adding theresult of discrimination to the recognition results provided by thetraffic environment recognizing means;

(5) The information merging means adds the result of identification ofthe recognition objects in connection with the traffic environmentrecognizing means to information produced by merging the recognitionresults provided by the plurality of traffic environment recognizingmeans;

(6) The information merging means has a function to demand the output ofthe recognition results from the traffic environment recognizing means;

(7) The plurality of traffic environment recognizing means includeinformation merging means, respectively; and

(8) The plurality of traffic environment recognizing means are connectedthrough a network to the information merging means.

According to a third aspect of the present invention, a vehicle isprovided with the foregoing traffic environment recognition system, anda vehicle control unit capable of controlling the traveling operation ofthe vehicle on the basis of the output information provided by theinformation merging means included in the traffic environmentrecognition system.

According to the foregoing means, the recognition results provided by atleast the two traffic environment recognizing means are merged toprovide merged information, the information identifying the recognitionobjects is added to the merged information, and the merged informationwith the information identifying the recognition objects is provided.Thus, highly reliable traffic environment recognition information can beprovided. The recognition objects may be other vehicles, movingdirections of the other vehicles, the relative speeds of other vehicleswith respect to the host vehicle, and the widths of the other vehicles.

The traffic environment recognizing means may be, for example,image-processing devices capable of forming images of the environment ofthe host vehicle and processing the images, or radars, such asmillimeter wave radars or laser radars, capable of emitting an electricwave or a light beam to measure distances between the host vehicle andobjects in the environment of the host vehicle.

Load on the vehicle control unit can be reduced and the programming of avehicle control algorithm can be facilitated by giving mergedinformation produced by merging the recognition results provided by theplurality of traffic environment recognizing means and provided with theinformation identifying the recognition objects.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent fromthe following description of embodiments with reference to theaccompanying drawings in which:

FIG. 1 is a block diagram of a traffic environment recognition system ina first embodiment according to the present invention;

FIG. 2 is a block diagram of a road information acquisition unit;

FIG. 3 is a block diagram of a host vehicle provided with a vehiclecontrol unit;

FIG. 4 is a block diagram of assistance in explaining a processingprocedure to be executed by an information-merging unit;

FIG. 5 is a diagram of assistance in explaining a first sensorinformation adding method;

FIG. 6 is a diagram of assistance in explaining a second sensorinformation adding method;

FIG. 7 is a diagram of assistance in explaining a third sensorinformation adding method;

FIG. 8 is a diagram of assistance in explaining a recognition resultdemand sequence;

FIG. 9 is a block diagram of a traffic environment recognition system ina second embodiment according to the present invention;

FIG. 10 is a time chart of assistance in explaining the functions of thetraffic environment recognition system shown in FIG. 9;

FIG. 11 is a block diagram of a traffic environment recognition systemin a third embodiment according to the present invention; and

FIG. 12 is a block diagram of a traffic environment recognition systemin a fourth embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a traffic environment recognition system in a firstembodiment according to the present invention has an image-processingunit 1, a radar unit 2, a road information acquisition unit 3, aninformation-merging unit 4 and a network 5 interconnecting thosecomponent units. The network 5 is connected to a vehicle control unit 6.

The image-processing unit 1 includes a CCD camera (charge-coupled devicecamera) provided with a CCD, i.e., a traffic environment recognizingsensor, and an image processor. The image-processing unit 1 forms animage of the environment of a host vehicle, and processes the image torecognize information about distances between the host vehicle and othervehicles, the moving directions of other vehicles, the relative speedsof other vehicles with respect to the host vehicle and the widths ofother vehicles, road shape (straight or curved), lane type (cruisinglane or passing lane) and lane departure. The image-processing unit 1provides the results of recognition for recognition objects sequentiallyonto the network 5. The image-processing unit 1 determines the distancesbetween the host vehicle and other vehicles from the coordinates ofimages of other vehicles in the image formed by the CCD camera,recognizes the road shape through the enhancement of the boundariesbetween the road and while lines, and recognizes lane departure withrespect to the coordinates of the center of the CCD camera.

The radar unit 2 has a laser radar or a millimeter wave radar, i.e., atraffic environment sensor. The radar unit 2 emits an electric wave or alight beam to measure distances between the host vehicle and objects inthe environment, directions from the host vehicle toward the objects andthe relative speeds of the objects, and provides measured data on theobjects sequentially on the network 5.

The road information acquisition unit 3 has a navigation system 30,i.e., a traffic environment sensor, provided with a GPS antenna (globalpositioning system antenna) 31 as shown in FIG. 2. The road informationacquisition unit 3 receives information about latitude and longitudethrough the GPS antenna 31 from an artificial satellite, determines theposition of the host vehicle from the received information, compares thethus determined position of the host vehicle with a road map stored inthe navigation system 30 to find a road on which the host vehicle istraveling and a crossing toward which the host vehicle is traveling. Theroad information acquisition unit 3 reads road shape information(straight lane, right-turn lane, left-turn lane, road width) andinformation about regulation speeds from the road map, calculates adistance L to the nearest crossing, and provides recognized informationincluding the calculated results and the shape information on thenetwork 5. The road information acquisition unit 3 stores specificnumbers assigned to roads and crossings shown in the road map, i.e.,road numbers and crossing numbers, and provides the road number and thecrossing number on the network 5. If the navigation system 30 has aroute calculating function, the road information acquisition unit 3calculates an optimum route from a source to a destination, and givesinformation about the calculated optimum route.

The information-merging unit 4 is provided with a data processor. Theinformation-merging unit 4 receives measured pieces of informationprovided by the image-processing unit 1, the radar unit 2 and the roadinformation acquisition unit 3 through the network 5, i.e., the CAN(controller area network, a standard automotive network), merges thepieces of information, examines the recognized results, addsidentification information identifying the recognized object, i.e.,information indicating that the recognized results including a vehicleinterval, a azimuth and a relative speed are for the same vehicle, tothe merged information, and provides the merged information togetherwith the identification information on the network 5.

The vehicle control unit 6 (vehicle control means) controls thetraveling operation of the host vehicle on the basis of the informationprovided by the information-merging unit 4. As shown in FIG. 3, athrottle valve controller 61, a transmission controller 62 and a brakecontroller 63 are connected to the vehicle control unit 6. The throttlevalve controller 61 is connected to a throttle valve actuator 64included in an engine 67, the transmission controller 62 is connected toa transmission 65, and the brake controller 63 is connected to a brakeactuator 66. The throttle valve controller 61 controls the operation ofthe throttle valve actuator 64 according to a throttle valve controlsignal provided by the vehicle control unit 6 to regulate a throttlevalve included in the engine 67. The transmission controller 62 controlsthe transmission 65 according to a transmission control signal providedby the vehicle control unit 6. The brake controller 63 controls thebrake actuator 66 according to a brake control signal provided by thevehicle control unit 6.

When the vehicle control unit 6 generates the control signals forcontrolling the throttle valve controller 61, the transmissioncontroller 62 and the brake controller 63, the vehicle control unit 6 isable to program a vehicle control algorithm easily and to reducedecision processes because the merged information about the recognizedresults provided by the sensors (the image-processing unit 1, the radarunit 2 and the road information acquisition unit 3) is accompanied byinformation identifying the recognized object.

An information-merging procedure to be carried out by theinformation-merging unit 4 will be described with reference to FIG. 4.

A first information merging method makes a query to see if an object ofmeasurement by the radar unit 2 and an object of measurement by theimage-processing unit 1 are one and the same vehicle. If the response tothe query is affirmative, the vehicle width and a position in a lanemeasured by the image-processing unit 1 are added to the vehicleinterval, the azimuth and the relative speed measured by theimage-processing unit 1 and the radar unit 2. Sensor informationindicating the use of both the recognition results provided by theimage-processing unit 1 and the radar unit 2 may additionally be used asidentification information identifying the recognition object.

More concretely, when the information-merging unit 4 merges vehicleinterval, azimuth and relative speed measured by the radar unit 2, andvehicle interval, azimuth, relative speed, vehicle width and position ina lane measured by the image-processing unit 1, and when the vehicleintervals, the azimuth and the relative speeds measured by theimage-processing unit 1 and the radar unit 2 are identical respectively,i.e., when both the image-processing unit 1 and the radar unit 2measured information abut one and the same vehicle, informationindicating that pieces of the measured information are those for thesame vehicle is added to the information including the vehicle interval,the azimuth and the relative speed, and information indicating that theinformation was measured only by the image-processing unit 1 is added tothe pieces of measured information including the vehicle width and theposition in a lane.

When the image-processing unit 1 and the radar unit 2 measuredinformation about different vehicles, respectively, informationindicating that those pieces of information are those about differentvehicles is added to the merged information.

A decision as to whether or not the vehicle with which the radar unit 2made measurement and the vehicle with which the image-processing unit 1made measurement are one and the same vehicle can be made on the basisof whether or not the vehicle intervals and the azimuth measured by theimage-processing unit 1 and the radar unit 2 are similar and in setranges, respectively.

When the information-merging unit 4 attaches the sensor information tothe measured information, bits of 8-bit data are assigned to theimage-processing unit 1, the radar unit 2 and the road informationacquisition unit 3, respectively, and the bits for the image-processingunit 1 and the radar unit 2 are set to, for example, the 1 state whenpieces of the measured information are those about the same vehicle asshown in FIG. 5 or to the 0 state when the same are about differentvehicles.

When the information-merging unit 4 attaches the sensor information tothe measured information, two bits are assigned to each of first toseventh pieces of information, where the first piece of information isvehicle interval, the second piece of information is azimuth, the thirdpiece of information is relative speed, the fourth piece of informationis vehicle width and the fifth piece of information is position in alane, one of the two bits for an eighth piece of information is used toindicate sensor information, and the other bit (the last bit) for theeighth piece of information is used to indicate information indicatingwhether or not the vehicles as objects of recognition are one and thesame vehicle. In FIG. 6, the first to the third piece of information arethose measured by the radar unit 2, the fourth and the fifth piece ofinformation are those measured by the image-processing unit, and thelast bit of the eighth piece of information is set to the 1 stateindicating that the vehicles are one and the same vehicle. The first tothe third piece of information indicate that pieces of measuredinformation measured by the radar unit 2 and those of measuredinformation measured by the image-processing unit 1 are those about oneand the same vehicle; that is the measurements relating to the pluralityof measuring objects are those relating to one and the same vehicle. Themeasured results can be used as sensor information even when only themeasured results relating to a single measuring object are the same(measurements relating to one and the same vehicle).

As shown in FIG. 7, a message identification number “100” assigned tothe radar unit 2 may be attached to the measured results provided by theradar unit 2, a message identification number “200” assigned to theimage-processing unit 1 may be attached to the measured results providedby the image-processing unit 1, and the information-merging unit 4 mayattach a message identification number “300” to the merged informationobtained by merging the measured results provided by theimage-processing unit 1 and the radar unit 2, when the measured resultsprovided by the image-processing unit 1 and the radar unit 2 are thoserelating to one and the same vehicle. When the image-processing unit 1and the radar unit 2 measured information about different vehicles,respectively, a message identification number “400”, by way of example,indicating that the measured results provided by the image-processingunit 1 and those provided by the radar unit 2 relate to differentvehicles, respectively, is attached to the merged information.

A second information merging method may be used. The secondinformation-merging method provides the information-merging unit 4 withan output demanding function to demand measured results from theimage-processing unit 1, the radar unit 2 and the road informationacquisition unit 3. For example, as shown in FIG. 8, theinformation-merging unit 4 sends an information demand message throughthe network 5 to the image-processing unit 1, the radar unit 2 and theroad information acquisition unit 3 to demand measured results fromthose units 1, 2 and 3. Then, the image-processing unit 1, the radarunit 2 and the road information acquisition unit 3 send messagesrelating to the measured results through the network 5 to theinformation-merging unit 4 in response to the information demandmessage. The information-merging unit 4 receives the measured results,executes the information merging operation shown in FIG. 4 to producethe merged information, and provides the merged information providedwith the sensor information.

A traffic environment recognition system in a second embodimentaccording to the present invention will be described with reference toFIG. 9. The traffic environment recognition system in the secondembodiment executes a third information merging method. The trafficenvironment recognition system is the same in constitution as thetraffic environment recognition system in the first embodiment, exceptthat the traffic environment recognition system in the second embodimentis provided with a time signal generating unit 7 in addition to animage-processing unit 1, a radar unit 2 and a road informationacquisition unit 3. The time signal generating unit 7 provides timesignals, i.e., a synchronizing signal, sequentially on a network 5 tosynchronize the operations of the image-processing unit 1, the radarunit 2 and the road information acquisition unit 3.

Times needed for the image-processing unit 1, the radar unit 2 and theroad information acquisition unit 3 to carry out signal processingoperations are dependent on the situation and traveling mode of the hostvehicle, and hence operations of the image-processing unit 1, the radarunit 2 and the road information acquisition unit 3 need to besynchronized. For example, the complexity of images varies with thevariation of the traffic situation, and hence time necessary for theimage-processing unit 1 to recognize the preceding vehicle by processingan image is dependent on the traffic situation. Consequently, thesequence of time when the radar 2 performed measurement, time when theimage-processing unit 1 forms an image, and time when processedinformation provided by the radar unit 2 and the image-processing unit 1is given to the vehicle control unit 6 is dependent on the trafficsituation and, sometimes, such a time error causes an error in thecontrol operation of the vehicle control unit 6.

In the traffic environment recognition system in the second embodiment,the time signal generating unit 7 provides time signals sequentially onthe network 5, the image-processing unit 1 stores image input time whenthe image-processing unit 1 forms an image, the radar unit 2 storesmeasurement starting time when measurement is started, and the roadinformation acquisition unit 3 stores position calculating time when thecalculation of the position of the host vehicle using GPS is started.When recognition results provided by the image-processing unit 1, theradar unit 2 and the road information acquisition unit 3 are sent out,the image input time and the measurement starting time are added to therecognition results.

Referring to FIG. 1, the image-processing unit 1 forms an image of theenvironment of the host vehicle, and stores image information togetherwith image input time t(n) when the image is captured. Subsequently, theimage-processing unit 1 carries out an object recognizing process torecognize a desired object in the image, and sends a recognition resultand the image input time t(n) through the network 5 to theinformation-merging unit 4 after the completion of the objectrecognizing process.

The radar unit 2 emits an electric wave or a light beam in synchronismwith the time signal to start measurement at time t(n+m), stores thetime t(n+m), processes radar signals, and gives measured resultstogether with the measurement starting time t(n+m) to theinformation-merging unit 4.

Referring to FIG. 10, the image-processing unit 1 forms an image atimage input time t(n) earlier than the measurement starting time t(n+m)when the radar unit 2 starts measurement. Since a time necessary for theimage-processing unit 1 to process an image is different from a timenecessary for the radar unit 2 to process signals, sometimes time whenthe image-processing unit 1 sends recognition results to theinformation-merging unit 4 is later than time when the radar unit 2sends recognition results to the information-merging unit 4. If theinformation-merging unit 4 processes those recognition results as theyare, it is possible that those recognition results are decidedmistakenly to be those relating to different vehicles, even if thoserecognition results relates to a single vehicle.

The information-merging unit 4 compares the time t(n) attached to therecognition results provided by the image-processing unit 1, and thetime t(n+m) attached to the recognition results provided by the radarunit 2, rearranges the recognition results according to the result ofcomparison of the times t(n) and t(n+m), carries out a merging operationfor merging the recognition results provided by the image-processingunit 1 and those provided by the radar unit 2, and decides the identityof the recognition object relating to the recognition results.

The information merging process can be carried out on an assumption thatone and the same vehicle was recognized by both the image-processingunit 1 and the radar unit 2 if the times t(n) and t(n+m) are in apredetermined time interval range of, for example, 0.05 to 0.10 s, orcan be carried out on an assumption that different vehicles wererecognized by the image-processing unit 1 and the radar unit 2 if theinterval between the times t(n) and t(n+m) is longer than the upperlimit of the foregoing predetermined time interval range. It is alsopossible to decide whether the image-processing unit 1 and the radarunit 2 recognized one and the same vehicle or whether the samerecognized different vehicles, respectively, on the basis of the resultof examination of the recognition results and the times t(n) and t(n+m),

Referring to FIG. 11, a traffic environment recognition system in athird embodiment includes an image-processing unit 1 provided with aninformation-merging unit 41, a radar unit 2 provided with aninformation-merging unit 42, a road information acquisition unit 3provided with an information-merging unit 43, and a time signalgenerating unit 7. The information-merging units 41, 42 and 43 are thesame in function as the foregoing information-merging unit 4. Thetraffic environment recognition system in the third embodiment is thesame in other respects as the traffic environment recognition system inthe second embodiment shown in FIG. 9.

Since the information-merging units 41, 42 and 43 are internal devices,and the traffic environment recognition system does not need anyexternal information-merging unit, the traffic environment recognitionsystem can be manufactured at a reduced cost.

A traffic environment recognition system in a fourth embodimentaccording to the present invention will be described with reference toFIG. 12. This traffic environment recognition system is provided with aninformation-merging unit 69 having the same function as theinformation-merging unit 4 and included in a vehicle control unit 6provided with a vehicle control arithmetic unit 68 instead of aninformation-merging unit connected to a network 5. The trafficenvironment recognition system in the fourth embodiment is the same inother respects as that in the second embodiment shown in FIG. 9.

Although the traffic environment recognition systems in the foregoingembodiments use different means for recognizing the environment of thehost vehicle as traffic environment recognizing means, the same may useidentical traffic environment recognizing means. For example, aplurality of image-processing units similar to the foregoingimage-processing unit 1 may be disposed on different parts of the hostvehicle, recognition results provided by the plurality ofimage-processing units may be merged to provided merged information, andthe merged information may be provided together with identificationinformation identifying the recognition object.

When a vehicle is provided with both the traffic environment recognitionsystem and the vehicle control unit in each of the foregoingembodiments, a vehicle control algorithm for the vehicle control unitcan be easily programmed, functions and reliability of vehicle controloperations can be improved, safety can be improved, and the automaticoperation of a vehicle is realizable.

As apparent from the foregoing description, according to the presentinvention, recognition results provided by at least two trafficenvironment recognizing means are merged to produce merged information,and the merged information is provided together with identificationinformation identifying a recognition object relating to the recognitionresults. Thus, highly reliable traffic environment recognitioninformation can be provided.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than limitation and that changes within the purviewof the appended claims may be made without departing from the true scopeand spirit of the invention in its broader aspects.

1-15. (canceled)
 16. An environment recognition system comprising; aplurality of host vehicle environment recognizing units operativelyconnected to a network; distinguishing units for distinguishing resultsrecognized by each of the plurality of environment recognizing units,and information merging units for the recognized results distinguishedby the distinguishing units, wherein the merging unit adds a timeinformation and a position information of at least one recognized objectout of the plurality of recognized objects to the merged information.17. An environment recognition system according to claim 16, furthercomprising: a time signal generating unit for outputting a common timeinformation of each of the plurality of environment recognizing unit tothe network.
 18. An environment recognition system according to claim17, wherein the time information includes a measurement time.
 19. Anenvironment recognition system according to claim 18, wherein theinformation merging unit is configured to judge that a first objectrecognized by a the first of the environment recognizing units and asecond object recognized by a the second of the environment recognizingunits are the same when a time measured by the first environmentrecognizing unit and a time measured by the second environmentrecognizing unit are in a predetermined time.
 20. An environmentrecognition system according to claim 18, wherein the informationmerging unit is configured to judge that a first object recognized by afirst of the environment recognizing units and a second objectrecognized by a second of the environment recognizing units aredifferent when a time measured by the first environment recognizing unitand a time measured by the second environment recognizing unit are notin a predetermined time.
 21. An environment recognition method in asystem having a plurality of host-vehicle environment recognizing unitsoperatively connected to a network comprising; distinguishing eachresult recognized by each of the plurality of host-vehicle environmentrecognizing units, and information from merging each of the resultsrecognized and distinguished including adding time information andposition information of at least one recognized object out of theplurality of recognized objects to the merged information.
 22. Anenvironment recognition method according to claim 21, further comprisinggenerating a time signal for outputting common time information of eachof the plurality of environment recognizing unit to the network.
 23. Anenvironment recognition method according to claim 22, wherein the timeinformation includes measurement time.
 24. An environment recognitionmethod according to claim 23, wherein the information merging includesjudging that a first recognized object of the first environmentrecognizing unit and a second recognized object of the secondenvironment recognizing unit are the same when a time measured by afirst environment recognizing unit and a time measured by a secondenvironment recognizing unit are in a predetermined time.
 25. Anenvironment recognition method according to claim 23, wherein theinformation merging includes judging that a first recognized object ofthe first environment recognizing unit and a second recognized object ofthe second environment recognizing unit recognized are different when atime measured by a first environment recognizing unit and a timemeasured by a second environment recognizing unit are not in apredetermined time.